This disclosure relates to a single shaft heavy duty turbine and more particularly to a bolting device for connecting components of a gas turbine rotor.
A brief description of a gas turbine plant is given in Van Nostrand's Scientific Encyclopedia, Fourth Edition, Van Nostrand Company, Princetown, N.J. Pages 757-759. The turbine is one of several components whose combined action is the conversion of heat energy into work. Typically, such a plant consists of a gas turbine, an air compressor driven by the gas turbine, and a combustion chamber wherein a liquid fuel is injected and burned at constant pressure equivalent to that of the compressor discharge. The rotor of the single shaft heavy duty turbine is a complex unit made up of a number of different components which are attached and secured to each other.
Heretofore, a plurality of nuts and bolts have been used in the rotor to connect the compressor section to the turbine section. However during rotation of the rotor under actual operating conditions, these nuts are exposed to high relative air velocities or "windage" which is the friction between the rotor and the air within its casing. The use of standard nuts, e.g. hexagonally shaped nuts, may cause sufficient rotational friction between the nut and the air passing over it to cause horsepower losses and result in multiple excitations to the last stage compressor blades and exit guide vanes due to pressure wakes being fed back into the compressor gas stream. As used herein, the term "windage nut" means a nut specially designed to minimize resistance of air against the contacting surfaces of the nut during rotation of the rotor by eliminating the outer protruding portions of the nut.
It is therefore an object of the present invention to provide an improved windage nut having low bolt stresses and having substantially no windage.